<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>字体大小(font size)</title>
  <style>
    .font-size {
      font-size: 16px;
    }
  </style>
</head>
<body>
  <div class="font-size">字体大小FontSize</div>
</body>
</html>